The present invention relates to a novel control mechanism for switching off a lamp of a fluorescent lighting fixture having a plurality of lamps.
The dimming of fluorescent lamp has been proposed to conserve energy. Typically, a fluorescent fixture includes a ballast which provides an impedance to limit the current to a fluorescent lamp. Standard iron core ballast ar most commonly found in existing fluorescent fixtures. Replacement of a standard ballast with a dimming ballast would permit dimming of the fluorescent fixtures, but this requires a very expensive retrofit procedure.
U.S. Pat. No. 4,350,935, proposes the use of a circuit for dimming a fluorescent fixture with conventional ballasts. Unfortunately, the system proposed therein is quite expensive and necessitates complex wiring procedures. U.S. Pat. No. 4,523,130 also proposes a method of retrofitting a fluorescent fixture to provide a dimming of the same which requires a thorough reworking of the fixture.
U.S. Pat. No. 4,488,092 and Japanese patent application No. 50-1184443 describe illumination circuits which turn off one lamp of a pair of fluorescent fixtures using a pair of switches. Japanese patent application No. 52-138148 shows a pair of lamps which are alternately controlled by a relay in conjunction with SCR triggered by a capacitor.
None of the prior art references address the problem of controlling the operation of a pair of fluorescent lamps in order to illuminate the same one at a time or together by the operation of an existing line switch.
Overcoming the problems found in the prior art would be a great advance in the lighting industry.